The Internet has dramatically increased the potential for data, voice and video services for customers. Existing circuit-switched telephony systems, however, do not provide the foundation to support the growing need for bandwidth and new services required by both residential and business consumers. As a result, integrated access devices have been introduced to support Internet and related technologies as well as standard telephony service.
Integrated access devices often employ asynchronous transfer mode (ATM) functionality to multiplex data, voice and video traffic together onto a single network. ATM is a connection-oriented packet-switching technology in which information is organized into small, fixed length cells. ATM carries data asynchronously, automatically assigning data cells to available time slots on demand to provide maximum throughput. Compared with other network technologies, ATM provides large increases in maximum support bandwidth, support for multiple types of traffic such as data, video, and voice transmissions on shared communication lines, and virtual networking capabilities, which increase bandwidth utilization and ease network administration.
ATM traffic is routed through a telecommunications network at high speeds using a switching tag included in the ATM cells. The switching tag defines a virtual path (VP) and a virtual channel (VC) in the network through which the cells are routed. The use of virtual path and channel connections allows physical bandwidth in the network to be subdivided and separately utilized.
ATM manages virtual connections through an ATM management layer (M-Plane) that consists of a stream of operation, administration and management (OAM) cells associated with each virtual connection between network elements. The OAM cells may be segment OAM cells communicated between adjacent elements in a virtual connection or end-to-end OAM cells transmitted between source and termination elements in the connection.
As the number of virtual connections supported by a network element rises, the load on the central processor to recognize and provide supplemental processing for OAM cells also rises. The increased load can become cumbersome to manage and can interfere with normal traffic flow. Processor upgrades to handle OAM processing can be prohibitively expensive for many low-cost applications in which access devices are utilized.
One solution to reduce the overall processing load on a central processor is to off-load OAM processing to line cards within the network element. In this case, functionality is added to the line cards to perform header recognition and look-up at line-rates on the incoming ATM cell streams and for processing the OAM cells. While this provides a more scalable architecture, the added hardware complexity and costs are prohibitive for many low rate cards and applications.
The present invention provides an improved method and system for processing asynchronous transfer mode (ATM) operation, administration, and management (OAM) traffic in a telecommunications node. In particular, processing of OAM and other suitable traffic is distributed in the telecommunications node between line cards and a centralized switch processor to provide a low-cost scalable architecture for the node.
In accordance with one embodiment of the present invention, a method for distributed processing of traffic in a telecommunications node includes receiving a traffic stream at a line card of the telecommunications node. The traffic stream includes a plurality of discrete cells. The cells are forwarded from the line card to a centralized switch of the telecommunications node. The centralized switch identifies cells that are of a particular type. Cells of the particular type are returned from the centralized switch to the line card. The returned cells are processed at the line card.
More specifically, in accordance with the particular embodiment of present invention, the discrete cells are asynchronous transfer mode (ATM) cells. In this embodiment, the cells of the particular type are operation, administration, and management (OAM) cells having a loop-back indicator. Thus, the OAM cells are identified at the centralized switch and processed by a line card.
Technical advantages of the present invention include providing an improved method and system for processing management and other suitable traffic that is in need of specialized processing in a telecommunications node. In particular, processing of the traffic is distributed between a centralized switch processor and a line card or other suitable element in the telecommunications node. This alleviates the overall processing load on the centralized switch processor and allows other value-added processing to be performed by the centralized switch processor on a traffic stream.
Another technical advantage of the present invention includes providing an improved method and system for transmitting ATM traffic in a telecommunications system. In particular, ATM OAM cells are recognized by a centralized ATM switch and looped back to the receiving line card for processing. As a result, processing of the OAM cells is off-loaded to the line cards while header recognition and look-up on an incoming ATM stream is conventionally performed by the centralized ATM switch in connection with its normal switching activities. Thus, cost and board space on line cards with OAM processing functionality are reduced. In addition, the scalable management layer (M-plane) architecture insures that ATM switching capacity of the node is limited only by switch bandwidth, not processing power.
Still another technical advantage of the present invention includes providing a more scalable architecture for a telecommunications access device. In particular, processing of specified types of traffic is distributed between elements in a node to take advantage of parallel processing power of multiple processors spread across multiple elements. As a result, system cost is more directly proportional to functionality which allows low-cost solutions for low-rate and other limited applications.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, description, and claims.